Conventionally, as a device for heating a member to be heated in various industrial fields, the industrial furnaces have been used. Among the industrial furnaces, those heating the member to be heated by combusting a fuel containing a carbon generate a high temperature combustion gas containing carbon dioxide simultaneously with the heat generation by the combustion of the fuel. Then, the generated combustion gas was exhausted to the outside (hereinafter, the combustion gas exhausted to the outside may be referred to as the “combustion exhaust gas” or simply “exhaust gas”.). Recently, the adverse effect on the environment by the discharge of the high temperature exhaust gas, or the like has been problematic. Moreover, the effective collection and recycling of the heat of the combustion exhaust gas have conventionally been the tasks. Moreover, especially the problem of the generation of the exhaust gas containing carbon dioxide attracts the attention particularly recently for the global warming issue, or the like so that cutback of the carbon dioxide amount contained in the exhaust gas from the industrial furnace has strongly been demanded.
On the other hand, as to the firing furnace for firing a ceramic, or the like as an industrial furnace of a relatively small size, the measure for collecting the heat of the combustion exhaust gas or the measure for cutting back the carbon dioxide exhaustion amount have hardly been adopted so that the combustion gas containing carbon dioxide used for heating the member to be heated (member to be fired) has been discharged as it is to the atmosphere as the exhaust gas. In contrast, a method for collecting the heat energy of the exhaust gas by for example returning the exhaust gas emitted from the firing furnace main body again to the firing furnace main body has been proposed (for example, see the official gazette of the Japanese Patent Application Laid Open (JP-A) No. 2002-340482). According to the method, since a part of the heat energy of the exhaust gas is collected, the total amount of the used fuel can be cut back, however, the energy collection amount and the fuel cutback amount were not so large. Moreover, although the carbon dioxide amount generated thereby can be cut back, the cutback amount was not so large as well.